Inhibitory neuron migration and IPL formation in the developing zebrafish retina.
Bottom Line: Finally, HCs, iACs and dACs each undergo cell type-specific migration.In contrast to current hypotheses, we find that most dACs send processes into the forming inner plexiform layer (IPL) before migrating through it and inverting their polarity.By imaging and quantifying the dynamics of HCs, iACs and dACs from birth to final position, this study thus provides evidence for distinct and new migration patterns during retinal lamination and insights into the initiation of IPL formation.
Affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK.Show MeSH
Mentions: To visualize RIN migration, we made use of a transgenic zebrafish line in which the promoter of the gene that encodes the basic helix-loop-helix (bHLH) transcription factor Ptf1a drives the expression of DsRed in RINs (Jusuf and Harris, 2009). This allowed us to follow several Ptf1a+ cells located in apical parts of the retina (Fig. 1A; supplementary material Movie 1). All of these cells exhibited elongated bipolar morphologies as they migrated basally towards the centre of the retina (Fig. 1A, 0 min). Moreover, it became clear that most of these cells retracted their apical processes only after they reached the middle of the retina (Fig. 1A, 150 min). Multipolar Ptf1a+ cells in the apical part of the INL (i.e. HCs) became apparent only later (Fig. 1A, 540 min). These observations suggested that many RINs begin their migration in a bipolar mode before switching to a multipolar morphology.Fig. 1.
Affiliation: Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3DY, UK.